The present invention relates to thermoplastic film structures having improved barrier and/or mechanical properties and methods for making the film structures. These improvements are achieved by incorporating into the thermoplastic film structures a polymeric nanocomposite comprising a polymer and nanosize particles of a modified clay.
It has been known to manufacture compositions which comprise modified clays in a polymeric base. These compositions are known as nanocomposites.
Carter, et al., U.S. Pat. No. 2,531,396 discloses a reinforced elastomer and a process for producing said elastomer which contains a modified clay. The clay of the invention includes montmorillonite, viz, sodium, potassium, lithium and other bentonites. The clay is characterized by an unbalanced crystal lattice which are believed to have negative charges neutralized by inorganic cations.
Frisk, U.S. Pat. No. 5,916,685 discloses a transparent multilayer laminate containing nanoparticulates having superior barrier properties to oxygen, water vapor and aromatic gases.
Frisk, et al., U.S. Pat. No. 5,876,812 disclose a container made of polymeric material which contain nanoparticulates to increase barrier properties.
Frisk, et al., U.S. Pat. No. 5,972,448 disclose a container made from a polymer material which has been integrated with a plurality of nanosize particles.
Serrano, et. al., U.S. Pat. No. 5,844,032 discloses the manufacturing of nanocomposites which are intercalated and combined with an EVOH matrix polymer.
Beall, et al., U.S. Pat. No. 5,952,095 disclose how to make specific intercalated nanoparticulates. The disclosure teaches nanoparticulates themselves, as well as methods of making them in addition to organic liquid compositions containing nanoparticulates.
Beall, et al., U.S. Pat. No. 5,880,197 disclose clays treated with organic molecules which when so treated intercalate the clay particles to create a matrix-like structure.
Beall, et al., U.S. Pat. No. 5,877,248 disclose a method of increasing the viscosity of an organic liquid by combining it with nanocomposite materials having specific characteristics/limitations.
Beall, et al., U.S. Pat. No. 5,578,672 disclose intercalates formed by mixing a phyllosilicate with a polymer and a liquid carrier, and extruding the mixture through a die-opening to absorb or intercalate the polymer between adjacent phyllosilicate platelets.
Christiani, et al., U.S. Pat. No. 5,747,560 disclose a process for making polymeric nanocomposite materials wherein the platelet particles have an average thickness equal to or less than about 50 xc3x85 and a maximum thickness of about 100 xc3x85.
Maxfield, et al., U.S. Pat. No. 5,514,734 disclose a process of forming nanocomposite material comprising a polymer matrix comprising a polymeric material and dispersed particles selected from the group consisting of platelet or fibrillar particles having specific characteristics.
Maxfield, et al., U.S. Pat. No. 5,385,776 disclose a composite formed from a gamma phase polyamide having dispersed therein a particulate material such as a phyllosilicate.
Alexandre, et. al., WO 99/47598, disclose a nanocomposite which is a dispersion of nanofiller particles derived from layered metal oxides or metal oxide salts. The nanocomposite is advantageously prepared by first swelling an untreated clay in water, then removing the water to form an organophilic clay that is dispersible in non-polar organic solvents. The organophilic clay can then be treated with an alkyl aluminoxane and subsequently a catalyst to form a complex that promotes olefin or styrenic polymerization and platelet dispersion, The nanocomposite can be prepared directly by in situ polymerization of the olefin or the styrene at the nanofiller particles without shear, without an ion exchange step, and without the need to incorporate polar substituents into the polyolefin or polystyrene.
Fischer, et al., WO 99/35185 disclose a method for preparing a nanocomposite material based on a polymeric matrix and a layered double hydroxide. The disclosure further relates to a nanocomposite material obtainable by such method and to a shaped article manufactured from such nanocomposite material.
Barbee, et al., WO 99/32403 disclose a composition comprising a polymer having dispersed therein at least one layered clay material which has been cation exchanged with organic cation salts; and at least one expanding agent which is compatible with said polymer. Preferred polymers include polyesters. The compositions of the disclosure show vastly improved platelet separation as evidenced by higher than previously reported basal spacing. The disclosure further relates to polyester composite materials having improved barrier useful for forming packages that have improved gas barrier properties.
Fischer, WO 99/07790 discloses a nanocomposite material on the basis of a clay having a layered structure and a cation exchange capacity of from 30 to 250 milliequivalents per 100 grams, a polymeric matrix and a block copolymer or a graft copolymer, which block copolymer or graft copolymer comprises one or more first structural units, which are compatible with the clay, and one or more second structural units, which are compatible with the polymeric matrix. Fischer further discloses a nanocomposite material wherein the clay has a cation exchange capacity of from 50 to 200 milliequivalents per 100 gram. In addition, Fischer discloses a nanocomposite material wherein the polymeric matrix is selected from the group consisting of polyolefins, vinyl polymers, polyesters, polyethers, polysiloxanes and acrylic polymers.
Li, et al., WO 98/53000 disclose toughened nanocomposite materials which are prepared based on a blend of one or more thermoplastic engineering resins, e.g., nylon, a functionalized, e.g., brominated, copolymer of a C4-C7 isomonoolefin, e.g., isobutylene, and a para-alkylstyrene, e.g., para-methylstyrene, and further contain a uniformly dispersed exfoliated phyllosilicate layered clay, e.g., montmorillonite. The nanocomposite materials exhibit superior mechanical properties, including enhanced impact strength. The composition of this disclosure may be extruded, compression molded, blow molded or injection molded into various shaped articles including fibers, films, industrial parts such as automotive parts, appliance housings, consumer products, packaging and the like. The resulting articles exhibit both high impact strength and low vapor permeability.
Matayabas, et al., WO 98/29499 disclose polyester-platelet particle composite compositions comprising about 0.01 to about 25 weight percent platelet particles dispersed in at least one polyester wherein said composition has an intrinsic viscosity of greater than about 0.55 dl/g, low shear melt viscosity greater than about 30,000 poise and a gas permeability which is at least 10% lower than that of unmodified polyester.
Frisk, et. al., WO 98/01346 disclose a container which is composed of a polymer material integrated with a plurality of nanosize particles of a clay mineral which act to enhance the barrier properties of the container. The polymer material may be PET, COPET or any mixture thereof. The nanocomposite polymer container decreases the permeability of various gases without substantially altering the fabrication method for producing containers composed of PET or COPET material, and without altering the containers themselves. The nanocomposite polymer containers of the disclosure are able to accomplish this due to the minimal amount of clay integrated with the polymer material, i.e., between 0.1% and 10% weight of the container. The small amount of clay provides a substantial barrier due to the high aspect ratios of the clay particles which will vary between 100 and 2000. The nanocomposite polymer container may be produced using in situ polymerization, solution intercalation, or melt exfoliation to integrate the clay mineral with the polymer material matrix. The clay mineral may be smectite, vermiculite, halloysite or any synthetic analog thereof, with a preference for the montmorillonite species of smectite clays.
This invention relates to polymeric thermoplastic film structures having improved barrier and/or mechanical properties wherein at least one layer of the thermoplastic film structure comprises a polymeric nanocomposite comprising a polymer and nanosize particles of a modified clay, and methods of making the polymeric thermoplastic film structures.